Hi Hans,

Thanks for your point and videobuf2 is also what I want to use.

But since our development kernel version right now is still 2.6.35, I need to 
find way to work with current videobuf framework.

Thanks
Wen

>-----Original Message-----
>From: Hans Verkuil [mailto:hverk...@xs4all.nl]
>Sent: 2011年2月9日 15:52
>To: Wang, Wen W; Jozef Kruger
>Cc: Kanigeri, Hari K; Iyer, Sundar; Yang, Jianwei; linux-media@vger.kernel.org
>Subject: Re: Memory allocation in Video4Linux
>
>On Wednesday, February 09, 2011 08:27:27 Wang, Wen W wrote:
>> Hi Hari,
>>
>> You are right. What we need is virtual address.
>>
>> Currently we alloc pages (alloc_pages()) for any request. Store those pages 
>> for an
>image buffer into a list. We also manage the virtual address for ISP by 
>ourself (the
>range from 0 to 4GB) and the page table for our MMU which is independent to 
>system
>MMU page table.
>
>Assuming you are using video4linux for this driver, then you should take a
>look at the new videobuf2 framework that will appear in 2.6.39. It is already
>in the media tree (http://git.linuxtv.org/media_tree.git, see
>include/media/videobuf2-core.h).
>
>It is much better than the old videobuf framework, and in particular gives
>the driver much more control on how memory is allocated and used.
>
>Regards,
>
>       Hans
>
>>
>> Thanks
>> Wen
>>
>> >-----Original Message-----
>> >From: Kanigeri, Hari K
>> >Sent: 2011年2月9日 15:22
>> >To: Iyer, Sundar; Wang, Wen W; Yang, Jianwei; linux-media@vger.kernel.org;
>> >umg-meego-handset-ker...@umglistsvr.jf.intel.com
>> >Cc: Jozef Kruger
>> >Subject: RE: Memory allocation in Video4Linux
>> >
>> >
>> >
>> >> -----Original Message-----
>> >> From: umg-meego-handset-kernel-boun...@umglistsvr.jf.intel.com
>> >> [mailto:umg-meego-handset-kernel-boun...@umglistsvr.jf.intel.com] On
>> >> Behalf Of Iyer, Sundar
>> >> Sent: Wednesday, February 09, 2011 12:20 PM
>> >> To: Wang, Wen W; Yang, Jianwei; linux-media@vger.kernel.org; umg-meego-
>> >> handset-ker...@umglistsvr.jf.intel.com
>> >> Cc: Jozef Kruger
>> >> Subject: Re: [Umg-meego-handset-kernel] Memory allocation in
>> >> Video4Linux
>> >>
>> >> I remember some Continous Memory Allocator (CMA) being iterated down a
>> >> few versions on
>> >> some mailing lists? IIRC, it is also for large buffers and management
>> >> for video IPs.
>> >
>> >I believe CMA is for allocating physically contiguous memory and from what 
>> >Wen
>> >mentioned he also needs virtual memory management, which the IOMMU will
>> >provide. Please check the open source discussion on CMA, the last I heard 
>> >CMA
>> >proposal was shot down.
>> >Reference: http://www.spinics.net/lists/linux-media/msg26875.html
>> >
>> >Wen, how are you currently allocating physical memory ?
>> >
>> >
>> >Thank you,
>> >Best regards,
>> >Hari
>> �翳�.n�����+%��遍荻�w��.n��伐�{炳g����n�r■�����ㄨ&{�
>夸z罐����zf"������������赙z_璁�:+v�)撸�
>>
>>
>
>--
>Hans Verkuil - video4linux developer - sponsored by Cisco

Reply via email to